• Cement Symposium
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• no.29
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• pp.194-200
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• 2002

• Explosives and Blasting
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• v.38 no.4
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• pp.46-52
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• 2020

Although anti-washout grouts are used extensively in underwater targets, major constraints continue to be associated with their use. These include poor bonding strength, poor pumpability, and loss of high strength in everyday engineering applications. In this study, based on the literature pertaining to self-compacted, non-dispersive, anti-washout grouts, a review of research trends in anti-washout grouts for underwater construction and sealing of karst cavities was carried out in order to determine the problems faced in this field. Grouts used under water suffer a loss of strength and bonding strength in comparison to grouts cast in air. Researchers are designing high-viscosity grouts to overcome the inrush of water and seal karst cavities; however, in doing so, they have inadvertently caused serious problems pertaining to the pumpability of these grouts and concretes in deep target locations. Thus, the majority of the anti-washout grouts and concretes that have been developed are not applicable to deep target environments, instead being suitable for only near-surface targets.

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.120-125
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• 2001

This paper describes the effect of fly ash replacement on the setting time of antiwashout underwater concrete, where cement was replaced by 0% to 50%. Experimental work was performed on the condition of sea water and in air to find out the characteristics of setting time between the concretes that were cast in air and cast in 15$^{\circ}C$ of sea water. The experimental results show that the setting time of underwater concrete with 50% replacement was delayed about 10 hours than normal concrete. And it can be concluded that, at the case of underseawater concrete addicted with fly ash, the delayed final setting times are shown as the function Tf=0.069F+7.69, where Tf is the delayed final setting time and F is quantity of fly ash, respectively. These results confirm that the setting time underseawater concrete could be prolonged.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.6
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• pp.74-82
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• 1996

In this study, the characteristics of antiwashout underwater concrete according to the using types of admixture were experimentally investigated. Especially, the comparison on the performance of seven types(CO-A, B, C, D, E, F, G) of the manufactured admixtures was carried out in the same mixing condition and proportions. Based on the results of experiments, the conclusions were summarized as follows : (1) The slump flow on most of specimens except by CO-F type were progressed very well. (2) In most of products, the measured values of suspensions, pH's and air contents were lower than their reference values. However, CO-B, CO-F and CO-G types exceeded the reference ones in suspension and pH. (3) The time lags between initial and final setting were about three hours in most of tests, however, the maximum difference of total setting time was ten hours in comparing with the admixture types. The unit weights were mostly lower than $2300kg/m^3$ and the compressive strengths cured by salt water were about 80% of the ones by fresh water. (4) Finally, in spite of some problems, most of the manufactured admixtures may be performed well their functions in antiwashout under-water concrete if the using quantities are properly controlled by the site experiments.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.231-239
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• 1999

When the concrete is cast at the sea, there are lots of restrictions in the working process being different from in land, and the concrete is suffered from the physical and chemical action in terms of marine environment. The compressive strength was measured after antiwash out underwater concrete mixed with fly ash had been cast and cured in order to produce the endurable high performance concrete, and then its characteristic was discussed by comparing one cured in air with in fresh water, and the effect of fly ash usage under the properly controled sea water temperature of $15{\pm}3^{\circ}C$ was also covered. The present work showed that the proper usage of fly ash was obtained at the condition of around 10% of substituted binder weight under the structure required the early age strength, and at the condition of over 40% if considering its durability and economy.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.91-97
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• 2003

At present, the antiwashout underwater concretes are used as popular construction materials in European countries, the United States and Japan. The water-soluble polymers in the antiwashout underwater concretes provide excellent segregation or washout resistance, self-compaction and self-leveling property to the concretes. The purpose of this study is to recommend to optimum mix proportions of antiwashout underwater concretes according to compressive strength of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$. The antiwashout underwater concretes are prepared with various unit cement content, unit water content, sand-aggregate ratio, unit antiwashout agent and superplasticizer content. And they are tested for flowability, and compressive strength. From the test results, it is possible to recommend the optimum mix proportions of antiwashout underwater concretes according to compressive strengths within the range of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.40-45
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• 2008

This paper describes the effects of fly ash replacement on the water tightness of antiwashout underwater concrete, which replaced the cement with fly ash from 0% to 30%. The experimental work was performed to find out the depth of permeation of concrete specimens cast in air and cured in 23 $^{\circ}C$ tap water using an open center pressure type of water permeation tester. The results showed that the permeation depth values of antiwashout underwater concrete were deeper than normal concrete, but that an admixture using fly ash during antiwashout underwater concrete casting in air made it more watertight than normal concrete according to the water permeation testing. SEM observations of the specimens of fly ash antiwashout underwater concrete showed that it wasmore packed with structures because of the pozzolan reaction of the fly ash and cement.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.83-86
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• 1998

Recently, underwater concrete constructions are increasing. Therefore it is considered important to control the quality of underwater concrete. In this paper, we have an intention of evaluating fundamental properties of underwater concrete using the Ground Granulated Blast Furnace Slag (GGBF Slag). Thus, it has been investigated that the slump flow of the concrete, pH value and suspended solids in solution, compressive strength on both of specimens made above and below water. Also the percentage of GGBF Slag was found to alter the filling-up in underwater concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.451-454
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• 2000

Recently, the antiwashout underwater concrete has been increasingly used for underwater structure such as high strength massive concrete structures. However, Concrete has poor quality ad durability due to dilution with separating cementitious material. In this study, specimens were made with antiwashout underwater concrete replaced with mineral admixtures to improve their properties and were placed in air, water, and salt water. To estimation the chloride ion permeation in concrete, ASTM C 1202 Test was performed. The experimental results demonstrate that the increase of the admixtures improved the properties of antiwashout underwater concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.117-122
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• 1996

The purpose of this study is to investigate the properties of underwater concrete using three kinds of cellulose ether which has viscosity and water retention. The result is that water retention in underwater concrete shows in inverse proportion to PH value and the compressive strength is almostly effected by water retention. It can be certificated by the zeta electro potential value of an undispersed underwater concrete.